Such a circuit breaker is described in patent document FR-A-2 696 274 filed on Sep. 29, 1992, by the Applicant.
According to that document, the first means for preventing the piston from moving are constituted by a spring disposed between the drive member and the piston, and by a fixed retaining member which co-operates with the piston, and the second means for displacing the piston axially are constituted by a drive member secured to the moving contact assembly, which member drives an abutment secured to the piston during the second portion of the displacement of the moving contact assembly, said abutment being disposed on the path of the drive member.
In such a circuit breaker, it turns out that the spring must be dimensioned to withstand the particularly high pressure that is exerted on the piston and that obtains within the compression chamber. Such a spring is expensive.
In addition, its force has repercussions throughout the drive and control system of the circuit breaker, which must be designed and dimensioned accordingly.
Finally, depending on the specific dimensions of the circuit breaker and on the maximum pressure that appears in the compression chamber, it is necessary to install a spring that delivers a particular force. The spring must therefore be matched and selected as a function of the type of circuit breaker.